Fan Motor Reinstallation & Commissioning at Octagon, Colchester

Client / Site: Octagon, Colchester
Date: 18th March 2026

These fans have been in service for approximately 45 years and, through consistent and effective maintenance by the site team over the years, have continued to operate reliably. They originate from a time before the use of inverter drives and were designed to operate within variable air volume (VAV) systems, where fan duty was adjusted throughout the day by varying the angle of the impeller blades, whilst the fan is in operation, the same as we achieve now using modern speed control methods.

In this instance, access to the fan was particularly restricted. Aside from some refurbishment works required to the motor, the fan itself remains in good operational condition. The client’s preference was to retain the existing unit, thereby avoiding the need for more invasive alterations to the wider system. A time will come when the plant will need updating, but for now the fans remain efficient and fully operational.

Take a look at these fantastic images from the original construction of the Octagon Building, in 1981.

The challenge wasn’t the work itself; it was getting to the kit. The plant room access was tight, and the motor’s weight made conventional handling impractical. Gibbons’ team set up a bespoke lifting frame over the fan and used an electric stair climber to safely manoeuvre the fan out to allow the motor to be removed. All the time being very careful with the 45-year-old variable pitching mechanism.

Once the motor works were complete in Gibbons’ workshop, the fan assembly was rebuilt in situ, with particular attention given to the variable pitch impeller. The unit was then reinstated into the existing ductwork, mechanically secured, and reconnected to the original electrical and control systems.

With everything back together, the system was brought up to speed and observed under normal operating conditions. The result was smooth operation, and a stable performance with no vibration issues or electrical concerns. Hopefully providing more years of reliable service.

All works were completed over two visits. The system was handed back fully operational, the area left clean, and no follow-on works required. A good example of how Gibbons use their experience to extend the life of existing equipment, rather than simply replacing it. Even if it is now 45 years old!